Feeling wanted is something of a long buried memory for Marouane Fellaini following a miserable debut season at Old Trafford. But the towering Belgian looked like a man reborn as he was called from the bench, after Dries Mertens, to rescue his much-hyped side and get their World Cup off to a tense but ultimately successful start.

The Red Devils, who had not appeared at a World Cup for 12 years but have been called dark horses so often it has gone well beyond cliche, flattered to deceive against a robust Algeria side until the pair of substitutes helped overhaul a one-goal deficit deep into the second half.

One of the smoothest midfields in the competition misfired and spluttered, requiring a shift in style and an old fashioned goal to come to their aid. The scorer was the Fellaini who terrorised defences for Everton rather than the haunted figure of last season.

Belgium’s coach, Marc Wilmots, claimed afterwards that he always knew that the Algerians would tire and that his changes would have the desired effect, but his relieved expression as his side overhauled the Fennec Foxes in the last 20 minutes told a different story.

First Kevin De Bruyne crossed from deep. Fellaini’s distinctive mop rose and sent a header flashing into Rais M’Bolhi’s net only five minutes after he had replaced the Tottenham Hotspur midfielder Mousa Dembélé, one of several players to underwhelm.

Ten minutes later De Bruyne won the ball from Sofian Feghouli, the impressive Valencia forward who had earlier put Algeria ahead with a nerveless penalty. With the half-time substitute Mertens and Eden Hazard finally injecting some urgency, the pair combined on the counterattack and the Napoli player nervelessly slotted home the winner. Belgium, who almost added a third through another Fellaini header, were lucky to escape.

Too much choice can sometimes leave you paralysed. And Wilmots, who has shuffled the wealth of attacking talent at his disposal during the warm-up matches, appeared to have confused himself by the time this game kicked off. Fellaini, Mertens, Kevin Mirallas and Adnan Janujaz were left on the bench and he began instead with Dembélé, Axel Witsel and Nacer Chadli smothering the centre.

Hazard and De Bruyne, who has tended to take a more central role of late, began on the wings. It is a tribute to the array of options Wilmots has on the bench that he was able to put it right before the end. Mertens replaced Chadli, then the young Ligue 1 forward Divock Origi came on for the ineffective Romelu Lukaku. Finally, Fellaini was introduced. With each change, Belgium looked more likely to get back into the game.

Their style became more incisive and direct and the Algerian defence, visibly tiring after a stirring effort, began to wilt. By the end the Belgians had managed 10 shots on target to Algeria’s one. But Algeria, unjustly written off as this group’s likely makeweights but ranked above all their African rivals, refused to be intimidated and pushed Belgium all the way.

Some had speculated that the Red Devils might be porous at the back, despite conceding only four goals in qualifying, but few predicted that they would be quite so toothless going forward. Despite enjoying plenty of possession the Belgians were largely restricted to long-range shots from Chadli and Witsel that M’Bolhi proved himself equal to.

Where they had hoped to be liquid and incisive, they were largely ponderous and predictable. The Algerian defence, marshalled by the captain Madjid Bougherra, held firm as tension transmitted itself from the Belgian fans and on to the pitch.

On the rare occasions Hazard and De Bruyne managed to get behind the resolute and occasionally industrial Algerian defence, their crosses failed to find a misfiring Lukaku. Wilmots, 12 years to the day since he played in Belgium’s last match in a major tournament, against Brazil, was a study in frustration as he stood hands on hips in the technical area.

Mertens at last succeeded in introducing some urgency into proceedings. A fizzing cross from the left was parried by the flapping M’Bolhi but Witsel could not direct his header on target.

Hazard, whose manager had urged him to “take off the handbrake” but who still had a quiet first half, began to stretch the play. Long before half-time the players in red had been rolling their eyes at one another and remonstrating with arms outstretched.

Hazard and Lukaku were among seven Belgian players in the starting lineup who play in the English top flight. And it was one of that number, Jan Vertonghen, who was to blame for the Algeria opener. The Spurs defender, who plays at left-back owing to a dearth of specialists in the full-back positions, was caught ambling back towards his own goal at half speed.

Having allowed Feghouli to get the wrong side of him he hauled him to the floor. The tricky forward got up to calmly send Thibaut Courtois the wrong way and spark wild celebrations among the noisy contingent of Algeria fans breaking up the sea of Brazilian shirts sported by locals. Algeria had not scored a World Cup goal since they drew 1-1 with Northern Ireland at Mexico 1986, a run that took in five matches, including that dire 0-0 draw with England in Cape Town four years ago. They celebrated accordingly.

And they had looked on course for a famous victory before Wilmots shuffled his pack and called on Manchester United’s forgotten man. But despite the smile he sported as Mertens later disappeared under a pile of red shirts, the manager will have plenty more thinking to do before his side play Russia on Sunday.